A conventional electrical plug has its two prongs inserted into a receptacle for power connection. However, the prongs, when loosely pulled outwardly from the receptacle, may cause electric shock or injury when electrically conducted to a person or a child.
U.S. Pat. No. 5,252,082 disclosed a safety plug having its two prongs shielded by a casing during plugging operation of the plug. Such a casing may prevent the prongs from being contacted by a person or a child for safety purpose. However, when using such a plug, the casing for shielding the prongs may obstruct the normal plugging operation, thereby causing inconvenience use of the safety plug.
The present inventor has found the drawbacks of the conventional electric plug or safety plug and invented the present safety plug as stably fastened in a receptacle.